OG11紫-33

5. Carbon-14 dating reveals that the megalithic monu­ments in Brittany are nearly 2,000 years as old as any of their supposed Mediterranean predecessors.

(A)  as old as any of their supposed

(B)  older than any of their supposed

(C)  as old as their supposed

(D)  older than any of their supposedly

(E)   as old as their supposedly

请问这里的supposed是修饰什么的? their 是指谁呢?是momuments么?  their supposed是什么意思啊? 请高人翻译一下好么?

their修饰monuments

supposed修饰predecessors.